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View Full Version : Running lean with GTRS and Uni 440?



danphines
05-06-2012, 09:21 AM
Went out and did some logging on the car today to see why I would be running lean. Some background on the car, it is a 2000 1.8TQM with an ATP GTRS eliminator, 440cc green giant injectors, 440cc unitronic tune, and a 3 inch turbo back exhaust. I just installed an a/f gauge last week, the AEM UEGO. At wot, the wideband is showing around 13.2-13.4. I went out today and logged blocks 002, 031, and 115

Results- green section is a 2nd gear pull and yellow is the 3rd gear pull
http://i389.photobucket.com/albums/oo331/danphines/Vagcomlog1.png

Now I read that I have to take the O2 sensor voltages and multiply them by 14.7 to get the actual value. Doing that I get:

0.195- 2.866
0.28- 4.166
0.78- 11.466
0.78- 11.466
0.785- 11.54
0.73- 10.7
0.705- 10.36
0.67- 9.85
0.7- 10.29
0.67- 9.85
0.715- 10.51

Now when I compare that to the specified values:
0.02- 2.94
0.015- 0.22
0.79- 11.6
0.85- 12.5
0.895- 13.16
0.89- 13.08
0.855- 12.6
0.855- 12.6
0.865-12.7
0.86-12.64
0.87- 12.8

Now the a/f gauge is reading close to the values that are specified, however why is the actual reading of the primary O2 sensor reading so rich? Is that something that is normal of the narrow band O2 sensors?

Also I have been reading online that the a/f at wot should be around 11.8 not the low 13's that I am getting. Any thoughts on what could be causing this?

Any input is greatly appreciated. Thanks guys.

Seerlah
05-06-2012, 09:47 AM
What fuel pump and is there a way to check your fuel pressure during WOT pulls? What FPR are you using (I have my stock 4 bar still, if you need it for testing purposes)? Also, when was the last time you changed your fuel filter? Low 13s at WOT is too lean. I'm 11.8-12:1 at WOT.

danphines
05-06-2012, 09:52 AM
What fuel pump and is there a way to check your fuel pressure during WOT pulls? What FPR are you using (I have my stock 4 bar still, if you need it for testing purposes)? Also, when was the last time you changed your fuel filter? Low 13s at WOT is too lean. I'm 11.8-12:1 at WOT.

It is the stock fuel pump. I have not changed the filter yet, after 186,000 miles im sure it needs it. I plan on doing that next week. The tune asks for a 3 bar fpr so that is the one I am using. I know that the a/f is supposed to be between 11.8 and 12.1 at wot, but my confusion comes in at the specified a/f. That was ranging from 12.64 to 13.1 if you look at the second set of numbers in the first post. Why would the ecu not be requesting around 11.8?

danphines
05-06-2012, 03:40 PM
Got some new logs for you guys. Seems like the more runs I am doing, the leaner the car is getting. It got so bad that by the end of the run I had to stop cause the a/f was climbing to close to 17. All these logs are in 3rd gear. The colors on the second log are showing the separation of the 2 runs.
http://i389.photobucket.com/albums/oo331/danphines/vaglog2.png
http://i389.photobucket.com/albums/oo331/danphines/vaglog3.png

walky_talky20
05-06-2012, 04:30 PM
I would say, trust your wideband gauge. Your ATW has just a narrowband and is useless for AFR data outside of steady cruise or idling.

I believe the values you are showing from block 031 are just the o2 sensor voltages (the measurement given is "V" for volts, so I think that's what it is). In that case, a simple x14.7 does not get you AFR. You would have to refer to a chart like this to translate those values:

http://www.ztechz.net/sitebuildercontent/sitebuilderpictures/narrowbando2.jpg

If you check your values against this chart, you will see that before you hit the throttle, it is hanging around stoich. When you put the hammer down it goes rich and then seems to lean out over 3,000 rpms. That would seem to agree with your wideband gauge. With the narrowband values, it is easy to see that you have basically no data once it is out of stoich. You can only tell whether it is rich or lean, but not how much.

Seerlah
05-06-2012, 06:39 PM
I'm not the guy to blame your tune or anything, but...

Get your fuel filter replaced and take it from there. After that, try and get a good look at your FP while you are driving. I seen someone just use a gauge at the end of of a long hose placed into his feed line tap. Then he just had it basically laying on his windshield (fed through one of the grommets on the false firewall and had it sitting on the windshield by the brake fluid reservoir) so he could see the gauge in his cabin while he drove. Got the job done. Or maybe it was to check his oil pressure. Either way, technique will still worked.

danphines
05-06-2012, 06:58 PM
I'm not the guy to blame your tune or anything, but...

Get your fuel filter replaced and take it from there. After that, try and get a good look at your FP while you are driving. I seen someone just use a gauge at the end of of a long hose placed into his feed line tap. Then he just had it basically laying on his windshield (fed through one of the grommets on the false firewall and had it sitting on the windshield by the brake fluid reservoir) so he could see the gauge in his cabin while he drove. Got the job done. Or maybe it was to check his oil pressure. Either way, technique will still worked.

I would not think the tune would be bad since the guy i bought the set up from was running it with no problems on his car. I am hoping it is either just the fuel filter or the fuel pump for now.

Seerlah
05-06-2012, 07:23 PM
That's what it's looking like. The Walbro 255 will also be just fine for what you need, and is the cheapest.

http://www.highflowfuel.com/i-6924800-walbro-255lph-drop-in-fuel-pump-assembly-audi-a4-1995-2001.html (free shipping)

If it were me and was on crunch time, I would do that, replace fuel filter, Lucas injector cleaner (for good measure), and see how A/F ratios looks after that. The fuel filter should be replaced roughly every 50k miles. Mine has like 30k on it.

M-Hood
05-07-2012, 08:16 AM
Now I read that I have to take the O2 sensor voltages and multiply them by 14.7 to get the actual value.


That is incorrect for your car which is a narrow band 02 sensor, that can only be used for the wide band 02 cars. On the narrow band car the higher the reading the richer the AFR. You want to be getting 02 voltage readings right around .85 and as you can see your no where near that.

You should really be running a upgraded pump with this turbo setup. If you want to see if the pump is the issue just put a fuel pressure gauge on the feed line at the rail and watch it to see if the readings go up with the boost and then start to drop again. If the pressure drops it means the pump cant flow enough fuel to keep up with the amount the injectors are spraying into the cylinder.

danphines
05-15-2012, 02:08 PM
Well I replaced the pump and filter today, still running lean. WOT is between 12.8 and 14.0 depending on the rpm. Could the primary O2 sensor be causing this to happen?

M-Hood
05-15-2012, 02:21 PM
Well I replaced the pump and filter today, still running lean. WOT is between 12.8 and 14.0 depending on the rpm. Could the primary O2 sensor be causing this to happen?

If the 02 sensor is old and worn it can cause a lean reading, usually when this is an issue the fuel trim reading will start to increase since the ECU is always trying to add more fuel for he low 02 readings at idle and part throttle. A bad 02 sensor can also cause poor gas mileage.

danphines
05-15-2012, 02:32 PM
If the 02 sensor is old and worn it can cause a lean reading, usually when this is an issue the fuel trim reading will start to increase since the ECU is always trying to add more fuel for he low 02 readings at idle and part throttle. A bad 02 sensor can also cause poor gas mileage.

The gas mileage is fine, around 400 per tank. I am befuddled as to what else could be causing the engine to run lean. New fuel pump is the walbro 255 high flow and the new filter was put in. I am going to try swapping injectors tomorrow.

danphines
05-15-2012, 04:14 PM
Just replaced the line to the fpr, got it down to 12.8 to 13.2 at wot

danphines
05-16-2012, 12:18 PM
Installed new plugs and an inline fuel gauge this morning. Idle fuel pressure is 39psi. Is that normal for a 3 bar tune?

Avant Nate
05-16-2012, 12:32 PM
You need to disconnect the vacuum line for accurate reading

Seerlah
05-16-2012, 12:46 PM
Remove the line to the IM when engine is idle around 800rpm. It should read 43.5psi. But that is not the point. You want to see how it rises when in WOT/boost. Run a hose with 1/8npt male on one end for the fuel pressure gauge in-line adapter with 1/8" npt female on the other end for the gauge. You may have to rig this up yourself though.

This: http://www.summitracing.com/parts/GAR-J9028/
To this: 5/16" fuel line hose from your local auto parts store and fuel line clamps
To this again: http://www.summitracing.com/parts/GAR-J9028/
To: 1/8 npt male to 1/8 npt female adapter (for some oddball reason I can't find this on Summit, but I may have one laying around)
To: Your fuel pressure gauge

Just snake it up through the grommet in the false firewall, over by the brake fluid reservoir, and lay the gauge on your windshield so you can see what's your FP at WOT. Ghetto, but effective.

When was the last time you changed out your primary o2 sensor? They should be changed every 100k, and maybe even earlier with the added heat from your turbo kit. I personally would swap this out first. I actually just swapped mine out last week.

danphines
05-22-2012, 06:40 PM
For anyone following the thread, finally got the lean situation taken care of. Had a leak in the crankcase breather, and changed out the primary O2 sensor. Down to between 11.7 and 12.3

Seerlah
05-22-2012, 08:10 PM
Something so simple [:/]

danphines
05-30-2012, 02:04 PM
Back to running lean again [headbang] here are the codes I pulled today.


Wednesday,30,May,2012,16:29:39:47919
VCDS Version: Release 11.11.3 (x64)

Address 01: Engine Labels: 058-906-018-ATW.lbl
Control Module Part Number: 4B0 906 018 P
Component and/or Version: 1.8L R4/UNI G 0006
Software Coding: 07201
Work Shop Code: WSC 78640
VCID: 2E4DD8A0EA0C649
4 Faults Found:

16524 - Oxygen (Lambda) Sensor B1 S2
P0140 - 35-00 - No Activity
17544 - Fuel Trim: Bank 1 (Add)
P1136 - 35-00 - System too Lean
16514 - Oxygen (Lambda) Sensor B1 S1
P0130 - 35-10 - Malfunction in Circuit - Intermittent
17536 - Fuel Trim; Bank 1 (Mult)
P1128 - 35-10 - System too Lean - Intermittent

Readiness: 0000 0000

Seerlah
05-30-2012, 05:05 PM
Looks like your sensor is already taking a sh*t on you. Warranty?

danphines
05-30-2012, 05:12 PM
Seems weird that the sensor would already be going bad. I got it from the VW dealership so Im sure they would warranty it but I dont think that is the problem because this is the same code I had last time.

walky_talky20
05-30-2012, 05:21 PM
I'm thinking the malfunction code, could just be a resultant symptom of the lean issue. If the AFR is lean all over the map, the sensor won't have the waveform it is supposed to have. The ECU may misconstrue this as a "circuit malfunction". Just a thought.

Seerlah
05-30-2012, 05:21 PM
I came to that conclusion by your sensor fixing the issue, then all of a sudden your issue is back. New boost leak test and MAF logs?

danphines
05-30-2012, 07:31 PM
ok, went out and did some logs. Color coded again for your viewing pleasure. First run is yellow, 2nd is orange. Both were done in 3rd gear up to about 6krpm, Anything over 6 makes me uncomfortable.

http://i389.photobucket.com/albums/oo331/danphines/log1.png

The log confuses me on the second run, the specified 02 voltage is different than the first run, and they were done in the same gear.....

http://i389.photobucket.com/albums/oo331/danphines/log11.png

Seerlah
05-30-2012, 07:49 PM
May sound like a dumb idea, but try electrical parts cleaner on the o2 sensor connector (engine harness and sensor).

danphines
05-30-2012, 08:47 PM
It can't be the connector because I replaced it with a new one when I replaced the O2 since it came with a new connector from audi. I'm leaning towards fuel injectors at this point. I just need to find my other set of 440s and give them a shot. Otherwise I'm slapping an afpr on and calling it a day

danphines
06-29-2012, 10:28 AM
Anyone looking up this thread for an answer, I FINALLY figured it out. First off, I had a brain fart when I thought that increasing the fuel pressure at the rail with an afpr would do anything since the engine is only going to give enough gas for the air going through the MAF so needless to say that did not work. Problem turned out to be one of the crank case breather hoses that connects to the suction jet pump as well as the suction jet pump itself both had holes in them causing unmetered air to get into the system. Sealed all of the holes up and now there is no more lean problem.

grillhands
06-30-2012, 09:08 AM
Anyone looking up this thread for an answer, I FINALLY figured it out. First off, I had a brain fart when I thought that increasing the fuel pressure at the rail with an afpr would do anything since the engine is only going to give enough gas for the air going through the MAF so needless to say that did not work. Problem turned out to be one of the crank case breather hoses that connects to the suction jet pump as well as the suction jet pump itself both had holes in them causing unmetered air to get into the system. Sealed all of the holes up and now there is no more lean problem.

That's the reason why I took all that stuff out. When I first got my car I had vacuum leaks all over the place. Glad you got that figured out.

walky_talky20
06-30-2012, 09:13 AM
^Yep, I deleted all that crap, and just refreshed the actual necessary stuff. That SJP is a piece of crap. As far as I can see, it's only purpose is to cause problems.

danphines
06-30-2012, 10:50 AM
^Yep, I deleted all that crap, and just refreshed the actual necessary stuff. That SJP is a piece of crap. As far as I can see, it's only purpose is to cause problems.

It has 2 purposes, to cause problems and to make you shell out $50 at the dealership for a piece of plastic that I am sure cost less than $1 to make. Still worth the $50 to not see my AFR climb to 15.0 at 22psi.

danphines
07-14-2012, 09:07 AM
Saturday,14,July,2012,11:36:45:47919
VCDS Version: Release 11.11.3 (x64)

Address 01: Engine Labels: 058-906-018-ATW.lbl
Control Module Part Number: 4B0 906 018 P
Component and/or Version: 1.8L R4/UNI G 0006
Software Coding: 07201
Work Shop Code: WSC 78640
VCID: 2E4DD8A0EA0C649
3 Faults Found:

16496 - Intake Air Temp. Sensor (G42)
P0112 - 35-10 - Signal too Low - Intermittent
17544 - Fuel Trim: Bank 1 (Add)
P1136 - 35-00 - System too Lean
17536 - Fuel Trim; Bank 1 (Mult)
P1128 - 35-10 - System too Lean - Intermittent

Readiness: 0000 0000

I am going to take the car to get smoke tested on friday to check for any vacuum leaks. I checked the fuel trims from block 001 and at idle they shoot up to between 20 and 25%. When I pulled the long term fuel trims the first (add) value was +7% and the 2nd (mult) value was -6.8%.

Anyone have any ideas on what would cause the add value to be positive and the mult value to be negative?

Also will a bad iat sensor have any effect on the a/f ratio? This is the first time I have gotten a code for the iat sensor.

walky_talky20
07-14-2012, 11:02 AM
A very positive additive trim points to a low MAF value at idle (most probably un-metered air entry)
A very negative multiplicative trim points to a MAF value that is too high in boost (most probably a boost leak, and loss of metered air).

- The ability of the MAF to read "too high" and cause a negative trim points to a MAF that reads plenty good. Thus you can assume the positive idle trim is not caused by a bad MAF, but more likely unmetered air entry.

It is very likely both leaks are the same leak, at a place that sees vacuum at idle and boost under boost, obviously. Probably a leak at the manifold, then.

danphines
07-14-2012, 03:47 PM
A very positive additive trim points to a low MAF value at idle (most probably un-metered air entry)
A very negative multiplicative trim points to a MAF value that is too high in boost (most probably a boost leak, and loss of metered air).

- The ability of the MAF to read "too high" and cause a negative trim points to a MAF that reads plenty good. Thus you can assume the positive idle trim is not caused by a bad MAF, but more likely unmetered air entry.

It is very likely both leaks are the same leak, at a place that sees vacuum at idle and boost under boost, obviously. Probably a leak at the manifold, then.

A leak at the manifold would make sense to me, however I have been pressure testing it up to 7psi and have found nothing. When I checked the g/s at idle it seems to bounce between 3.2 and 3.6 g/s. Vacuum at idle is between 18 and 19 and in gear I am seeing 23 off throttle. Do these vacuum numbers seem a little low to anyone else? I thought they seemed just a tad low.

danphines
07-15-2012, 11:54 AM
Went out today and got a ton of new logs. Anyone willing to help just pm me your email and I will send them to you. Any help at all is greatly appreciated!